In GC, capillary columns need to be joined to various devices, such as injectors, detectors, and other column or tubing ends. Particularly in capillary chromatography, managing the volumes, flow rates, and geometries between devices has a critical effect on maintaining peak shape quality. There is a need for a union connector assembly that provides zero or near zero dead volume for GC columns.
Previous attempts to provide this type of union have produced connectors that are either too complex in terms of their operation, too large and bulky to be useful in smaller areas, or too unreliable in terms of their performance. Examples of such fitting are found in U.S. Pat. No. 5,540,464 and U.S. Pat. No. 5,288,113. The fittings disclosed in these references are especially unsuitable for use in the smaller ovens utilized in Micro Gas Chromatography (Micro GC).
Another common zero dead volume union which provide acceptable chromatographic performance is the tapered glass press fit union. This type of union, however, has certain drawbacks as well. The reliability of the tapered glass press fit union is inconsistent with temperature range cycling. Additionally, the integrity of the connection around bends is limited. Finally, this type of connector is not reusable.
The term Micro GC refers to a type of chromatography that is performed on an instrument that is smaller than a standard gas chromatograph. Typically in a Micro-GC, the column is coiled to 57 mm ID, and is positioned in an oven that is only 110 mm tall. The size of the connector assembly is a significant consideration in Micro GC. Previous connectors are too large or bulky to be practical for use in this size machine. There is a need for a zero or near zero dead volume connector assembly that is simple and reusable, There is a need for a connector assembly that is less bulky and more compact for smaller chromatographs, and one that provides a secure connection for straight or bent tubing.